Speaking-telephone receiver



(No Model.)

J. E OEEETSON.

SPEAKING TELEPHONE RECEIVER. No. 329,083. Patented Oct. 27, 1885* UNITED STATES PATrNr tribe.

JAMES H. ROBERTSON, OF BROOKLYN, NEW YORK.

SPEAKING-TELEPHONE RECElVER.

SPECIFICATION forming part of Letters Patent No. 329,083, dated October 27, 1885.

Application filed December 17, 1883. Renewed March 20, 1885. Serial No. 159,582. (No model.)

To all whom it may concern.-

Be it known that I, JAMES H. ROBERTSON, of the city of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement in Speaking-Telephone Receivers, of which the following is a specification.

My present invention relates to an improvement upon the instrument described in Letters Patent N 0. 289,309, granted to me November 27, 1883; and it consists in the combination of devices herein described and claimed.

The accompanying drawing represents the entire instrument, including a transmitter and receiver, in which A is the primary helix of an induction-coil; a a, the wires of the primary circuit, B being the battery, 0 the diaphragm, andD the vibrative contact-electrode of the transmitter in said circuit.

E is the secondary helix of the said induction-coil, in the circuit with which is the receiver, consisting of the electromagnet F and diaphragm G, the secondary circuit being by way of ground 0, wire 12, secondary helix of the induction-coil, wire I), diaphragm G, core d, and helix (2 of the electro-magnet F, wire b and ultimately to ground. (Not shown.) The core d of the receiving-magnet is hollow or centrally recessed, and within the recess is placed a spiral spring, f, the outer end of which carries an electrode, t, that is in contact with an electrode. in the circuit, and the opposite end abutting against a screw-plug, 9, that works in a screw-tapped opening in the inner end of the core d, which serves to regulate the tension of said spring.

So far as now described, this instrument is similar to the one described in my said Patent No. 289,309, before referred to but in the latter there is interposed between the diaphragm and the pole or poles of the electromagnet a vibrative armature attached to the outer end of the spring f, the said armature being provided with an electrode that is in contact with an electrode on the diaphragm, the secondary circuit being by the way of the core of the electro-magnet, the spiral spring, the said armature and the electrodes, and the diaphragm, .to ground, the diaphragm being either nonmagnetic or placed at a distance from the pole or poles of the magnet beyond the magnetic influence, and the vibrations of the diaphragm being produced mechanically by the magnet- 1 ically-produced vibrations of the said armature.

In my present receiver I dispense with the separate vibrative armature, and place the diaphragm, which is of metal, capable of magnetic induction, or carries attached to its center an armature, in such proximity to the pole of the magnet that it will be vibrated by variations of magnetism in the magnet, the circuit now being by way of helix E, wire b, to diaphragm G, spring f, core (2, wire I), helix 6, and wire b the current passing through the electrodes h and 1'. These electrodes may be of any suitable material.

I do not limit myself to the core 11 and spring f, located in the said core, as described, as the conducting medium between the electrode h and helix E. Any equivalent device or devices for the purpose may be employed.

' By this improvement which I have now described, theinstru ment is simplified and cheapened, while its efficiency is not impaired.

What I claim as myinvention, and desire to secure by Letters Patent, is-

In a speakingtelephone receiver in the secondary circuit of an induction-coil, in the primary circuit of which is the transmitter, the combination of the magnet and a diaphragm capable of magnetic induction, or carrying a piece of metal capable of magnetic induction, in front of the pole of the magnet and in close proximity thereto, so as to be actuated directly by the magnet, the said secondary circuit being arranged as described, whereby the secondary current passes through an electrode on the diaphragm, and another vibrative electrode in the said circuit in contact with the electrode on the diaphragm, as and for the purpose set forth.

JAMES H. ROBERTSON.

Witnesses:

A. G. N. VERMILYA, A. S. FI'roH. 

